The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Semiconductor memory devices, such as flash memory storage cards, are widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example cellular telephones, digital cameras, personal digital assistants, medical electronics, mobile computing devices, non-mobile computing devices and data servers.
Semiconductor memory may comprise non-volatile memory or volatile memory. Non-volatile memory allows information to be stored and retained even when the non-volatile memory is not connected to a source of power (e.g., a battery). Examples of non-volatile memory include flash memory (e.g., NAND-type and NOR-type flash memory), Electrically Erasable Programmable Read-Only Memory (EEPROM), and others.
Such semiconductor memory generally include one or more memory die and a controller die such as an ASIC mounted and electrically coupled to a substrate. The memory die and controller die may be wire bonded to the substrate, and then encapsulated in a mold compound to form a completed semiconductor package. Conventional NAND memory packages have a small number of data pins (eight), which enables sufficient tradeoff between today's system performance and costs. These data connections are routed through the packaging substrate before bonding again to the controller die. Therefore, the pad layout of conventional semiconductor memory dies have been optimized to enable wire bond connections to the substrate for both the memory die and controller die.
While a variety of semiconductor memory configurations are known, wide input/output (I/O) is a developing technology where stacked memory die may be mounted on a substrate. This methodology requires a much larger number of electrical connections between the memory die and substrate (>10×), which presents new challenges in the bonding, layout and yield of the electrical connections within the semiconductor package. Therefore, the industry is looking to migrate to through-silicon vias or other interconnect technologies to solve this problem, which presents much higher cost option.